Slide presentation programs are computer programs that enable a user to create, edit, manage, and perform "presentations" on a computer. One example of a popular slide presentation program is Microsoft PowerPoint, available from Microsoft Corporation, of Redmond, Washington. A slide presentation includes a set of electronic "slides," each slide corresponding to one screen or page of output. An electronic slide may also be converted to a 35 mm or overhead transparency and displayed in a standard slide projector or overhead projector. Each slide contains one or more objects, such as text, graphical images, or graphic animation. A slide may also include a sound object that is played when the slide is displayed during a "slide show" performance.
A slide presentation program "performs" a slide show by sequentially displaying a series of slides contained within the slide presentation. The slides are displayed on a computer screen or projected onto a separate surface. During a performance of a slide show, a "presenter" controls the performance by invoking commands to "advance" to the next slide. A command can be entered using a keyboard, a mouse, or another suitable input device. Alternatively, an author of a slide presentation can include slide "timings" with each slide. A slide timing corresponding to a slide indicates the number of seconds that the slide is displayed before the slide presentation program automatically advances to the next slide. During a performance of a slide show, a slide presentation program automatically advances to the next slide when the current slide's timing ends. An ordered sequence of slides is predetermined by a slide presentation author. During a performance of a slide show, a presenter can enter commands to alter the sequence of slides.
An audio file containing audio data can be optionally associated with each slide of a slide presentation. During a slide show, when a slide is displayed, the slide presentation program retrieves the audio file associated with the slide, if any, and plays the sound represented by the audio data within the file. "WAV" and Musical Instrument Digital Interface (MIDI) are two well known formats for storing audio data. The Audio Interchange File Format (AIFF) is a well known format for storing audio data on Apple Macintosh computers.
In order to create a slide presentation that has an accompanying soundtrack, such as a music soundtrack, an author creates or locates appropriate audio files to embed in the presentation, and then associates an individual audio file with each slide, in an appropriate and aesthetically pleasing sequence. During a slide show, if the playing of an audio file is interrupted before completion, the soundtrack stops abruptly. If transition to a new slide results in the playing of a second audio file while a first audio file is playing, the first audio file is abruptly terminated before beginning the second audio file. It is therefore difficult to create and present an aesthetically pleasing soundtrack to accompany a slide show. It is also difficult to create and perform a soundtrack that is appropriate to specific slides within a slide presentation.
It is desirable to have a mechanism that allows a slide presentation author to designate the creation and playing of an aesthetically pleasing and appropriate soundtrack during a slide show. Preferably, such a mechanism will provide a slide presentation author with a way to specify the type of soundtrack that is created and played to accompany the display of each slide during a slide show. Additionally, a preferable mechanism will automatically create aesthetically pleasing transitions between music segments when changes occur during a slide show, either as a result of specifications by an author, or control by a slide show presenter. Further, a preferable mechanism will provide a presentation author with a way to designate that short musical "motifs" are to be played upon the occurrence of certain events. The present invention is directed to providing such a mechanism.